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#11
Your hard disc S.M.A.R.T. data looks good. The disc only has 855 hours. You should run a short test and long test as well. If Western Digital has a utility to do a full erase or low level type format (old terminology), then you should run that also. I would just test the disc, do a full erase and then perform a clean install per the tutorial link posted above with what ever version of Win 7 you have with a good COA. You shouldn't have any issues if you follow the tutorial. A clean install resolves a lot of issues and gives you a good as new pc.
You can use this disc as a system backup drive if you get the new disc. This disc is barely broken in.
You should get a good DVD burner (internal if you've got the space). They don't cost that much and they're very useful.